Hybrid cycle combustion engine and methods

ABSTRACT

A method of operating an internal combustion engine having a housing, a piston mounted in the housing for complex motion about a plurality of axes and coupled to a shaft, and wherein occur phases of compression, combustion, and expansion in the housing, and wherein, in the compression phase, air introduced through an intake port into the housing is compressed by reducing volume of a compression chamber in the housing from an initial volume to a second volume that is less than the initial volume, and in the expansion phase, byproducts of combustion expand from the second volume to a third volume that is greater than the initial volume.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of U.S. patent applicationSer. No. 14/326,161, filed Jul. 8, 2014 [practitioner's file 2972/128],which is a continuation of U.S. patent application Ser. No. 13/758,122,filed Feb. 4, 2013 [practitioner's file 2972/122], now U.S. Pat. No.8,794,211, which is a continuation of U.S. patent application Ser. No.10/585,704 filed Mar. 28, 2008 [practitioner's file 2972/103], now U.S.Pat. No. 8,365,698, which claims priority to PCT Patent Application No.PCT/US2005/000932 filed Jan. 12, 2005, which claims priority to U.S.Provisional Patent Application No. 60/535,891 filed Jan. 12, 2004, thedisclosures of which are incorporated by reference herein in theirentirety.

TECHNICAL FIELD

The present invention relates generally to internal combustion engines,and, more particularly, to four-stroke variable-volume internalcombustion engines and related methods.

BACKGROUND ART

A variety of conventional internal combustion engines (“ICE”) known inthe art, in spite of almost 150 years of development, still suffer fromlow efficiency, high levels of harmful exhausts, and load-dependentperformance, among other shortcomings. The efficiency of heat engines isgenerally low due, at least in part, to theoretical thermodynamiclimitations of ideal cycles, as well as additional energy losses due todeviations from ideal cycles and friction between moving parts.Typically, only up to about 30% of the chemical energy of the fuel isconverted into useful work. About 40% is removed as heat by coolingwater, while the remaining 30% is lost with exhaust gases.

In addition, various gases, harmful for the environment and humans, suchas unburned fuel, NOx and others are formed as a byproduct of engineoperation, mainly due to a very limited ability to control thecombustion process. Further, the efficiency of heat engines is optimizedfor a narrow range of power loads. In reality, these engines seldomoperate in these optimal ranges, thus operating efficiency is reduced.

The LPPE engine, disclosed in international application No.PCT/US03/05749 filed on Feb. 26, 2003 (International Publication NumberWO 03/074840), incorporated herein by reference, while having a numberof important advantages, may have few disadvantages, such as largeamount of water that has to be pushed during each cycle and need forcomputer control.

SUMMARY OF EMBODIMENTS

Various embodiments of the present invention, which implement a HybridCycle Combustion Engine (HCCE) and related methods, offer solutions tosome of the problems inherent in prior art approaches.

In general, in one aspect, the invention is directed to an improvedmethod for operating an internal combustion engine of the four-strokevariable volume type that has a compression stroke for compressing aworking medium and a power stroke. An important feature of this aspectof the invention includes refraining from introducing substantial amountof fuel into the working medium during the compression stroke untilsubstantially maximum pressure of the working medium has been reached.Various embodiments of this aspect of the invention include the step ofcausing the compression stroke to produce a pressure of the workingmedium that would cause auto-ignition when fuel is added to it. Inaddition, some embodiments of this aspect of the invention include atleast one of the following steps:

(a) causing combustion of fuel under substantially constant volumeconditions; and

(b) causing the power stroke to provide a larger volume to combustionproducts than the compression stroke provides to the working medium. Infurther related embodiments, both processes (a) and (b) are utilized.Optionally, the power stroke is implemented with a non-reciprocatingmember, such as a “recip-rotating” piston (as that term is definedbelow). Also optionally the compression stroke is implemented with anon-reciprocating member, such as a recip-rotating piston.

Generally, in another aspect, the invention features an internalcombustion engine that includes:

-   -   (a) a first housing at least partially defining a compression        chamber for reducing volume of a working medium introduced        thereto;    -   (b) a second housing at least partially disposed within the        first housing and defining at least one combustion chamber in        periodic communication with the compression chamber for        receiving the working medium therefrom;    -   (c) a means for introducing a fuel medium into the combustion        chamber; and    -   (d) a third housing at least partially defining an expander        chamber in periodic communication with the combustion chamber        for increasing volume of by-products generated during combustion        of the fuel medium mixed with the working medium in the        combustion chamber.

Optionally, the engine has a first movable member at least partiallydisposed within the compression chamber for directing the working mediuminto the combustion chamber. The first movable member may define atleast two subchambers within the compression chamber, the subchamberscharacterized by a variable volume. The first movable member mayoptionally be a rotatable piston, a reciprocal piston, or arecip-rotating piston. Also optionally, at least one of the secondhousing and the first movable member has a means for controllablysealing the combustion chamber, such as, for example, a fluidic diode.

In related embodiments, the engine includes a means for introducing afluid medium into at least one of the compression chamber, thecombustion chamber, and the expander chamber. Optionally, the engineincludes a heat exchanger for recovering the fluid medium from theexpander chamber and for increasing heat of combustion of the fuelmedium prior to introduction thereof to the combustion chamber.

Alternatively or additionally, the engine includes a second movablemember disposed at least partially within the expander chamber, thesecond movable member reacting against the combustion by-productsentering from the combustion chamber. As in the case of the firstmoveable member, the second movable member may define at least twosubchambers within the expander chamber, the subchambers characterizedby a variable volume. The second movable member may optionally be arotatable piston, a reciprocal piston, or a recip-rotating piston.

In further related embodiments, the second housing is rotatable inrelation to at least one of the first housing and the third housing. Thefirst housing and the third housing may optionally be a unitary housingstructure. Similarly the compression chamber and the expander chambermay be implemented as a single chamber characterized by a variablevolume.

Generally, in yet another aspect, there is provided an internalcombustion engine that includes:

-   -   (a) a first housing at least partially defining a compression        chamber for reducing volume of a working medium introduced        thereto;    -   (b) a first movable member at least partially disposed within        the compression chamber for directing the working medium into        the combustion chamber;    -   (c) a second housing at least partially disposed within the        first housing and defining at least one combustion chamber in        periodic communication with the compression chamber for        receiving the working medium therefrom;    -   (d) a means for introducing a fuel medium into the combustion        chamber;    -   (e) a third housing at least partially defining an expander        chamber in periodic communication with the combustion chamber        for increasing volume of by-products generated during combustion        of the fuel medium mixed with the working medium in the        combustion chamber; and    -   (f) a second movable member disposed at least partially within        the expander chamber, the second movable member reacting against        the by-products entering from the expander chamber, at least one        the first housing, the second housing, the first movable member        and the second movable member defines at least one fluidic diode        for controllably sealing at least one of the compression        chamber, combustion chamber, and the expander chamber.

In various embodiments of this aspect of the invention, the engineincludes a sealing fluid unidirectionally movable through the at leastone fluidic diode

In yet another aspect of the invention, there is provided a structurehaving a controllably sealable chamber. The structure includes a housingmember having an interior surface defining the chamber; and an innermember at least partially disposed within the chamber, the inner memberhaving an outer surface and, at least one of the housing member and theinner member being movable such that the housing member and the innermember are movable relative to each other in such as way that at least afirst portion of the outer surface of the inner member is disposableproximate to a first portion of the interior surface, at least one ofthe first portion of the outer surface of the inner member and the firstportion of the interior surface of the housing member defining at leastone fluidic diode. A sealing fluid unidirectionally movable through theat least one fluidic diode may optionally be provided.

In still another aspect, in general, the invention features a method forenergy conversion that includes the steps of:

-   -   (a) introducing a working medium into a compression chamber        characterized by a first volume value;    -   (b) controllably reducing the volume of the working medium to a        second volume value thereby compressing the working medium;    -   (c) combining a fuel medium with the compressed working medium        thereby obtaining a combustible mixture of the fuel medium and        the compressed working medium, the mixture characterized by a        third volume value;    -   (d) combusting the mixture to produce a volume of combustion        by-products; and    -   (e) maintaining the volume of combustion by-products generated        during combustion of the mixture at or below the third volume        value.

Optionally, the method according to this aspect of the inventionincludes the step of increasing the volume of the combustion by-productsto a fourth volume value, the fourth volume value exceeding the firstvolume value; the step of increasing the volume of the combustionby-products optionally including transferring the combustion by-productsto an expansion chamber characterized by the fourth volume value.

The working medium may be air or a noncombustible mixture of air andfuel medium. Optionally, the temperature of the working medium may beadjusted so that the working medium is compressed substantiallyisothermally. Also optionally, there may be added a fluid medium, suchas water, to the working medium during compression. The method may beimplemented to include reducing temperature of the combustionby-products while increasing heat of combustion of the fuel medium priorto combining thereof with the compressed working medium.

In further related embodiments, the second volume value equals the thirdvolume value, and controllably reducing the volume of the working mediummay include transferring the working medium to a combustion chambercharacterized by the third volume value. Alternatively or in addition,combusting the mixture may include igniting the mixture of the fuelmedium and the compressed working medium. Optionally, maintaining thevolume of combustion by-products may include adding a fluid medium tothe mixture.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like reference characters generally refer to the sameparts throughout the different views. Also, the drawings are notnecessarily to scale, emphasis instead generally being placed uponillustrating the principles of the invention. In the followingdescription, various embodiments of the present invention are describedwith reference to the following drawings, in which:

FIG. 1 is pressure/volume diagrams for a typical Otto cycle, shown indashed lines, as well as for an engine using an HCCE, shown in solidlines;

FIG. 2 is a block-diagram of a HCCE, according to various embodiments ofthe invention;

FIG. 3 is a liquid-piston implementation of the High Efficiency HybridCycle (HEHC);

FIG. 4 is a comparison of energy distribution within conventional ICEand HCCE;

FIG. 5 shows more detailed energy balance sheet for HCCE;

FIG. 6 depicts a liquid-piston based HCCE in which combustion chambersare integrated with cylinders;

FIGS. 7 and 8 depicts a liquid-piston based HCCE with standalonecombustion chambers;

FIG. 9 depict combustion chamber/exhaust/intake valve of the HCCRaccording to one embodiment of the invention;

FIG. 10 depicts details of operation of the liquid-piston based HCCEwith standalone combustion chambers;

FIG. 11 depicts an exemplary modification of the liquid-piston basedHCCE with standalone combustion chambers;

FIGS. 12-20 depict various embodiments of the HCCE in which the amountof liquid can be made arbitrarily small;

FIGS. 21-26 provide construction details and explain principles ofoperation of a large-angle oscillating piston design of HCCE accordingto some embodiments of the invention;

FIG. 27 depicts an embodiment of the large-angle oscillating pistondesign of HCCE.

FIGS. 28-33 provide construction details and illustrate principles ofoperation of a particular embodiment of the HCCE based on constant widthpiston design.

FIG. 34 depicts various embodiments of the design based on constantwidth piston of FIGS. 28-33;

FIG. 35 is a different potential application for the modified Reuleauxtriangle shaped piston;

FIGS. 36-40 provide construction details and illustrate principles ofoperation of an embodiment of the HCCE based on constant width chamberdesign;

FIG. 41 depicts still another embodiment of the HCCE based on scissorpistons design;

FIGS. 42A and 42B show the sequence of positions of pistons undergoingfour HEHC strokes;

FIG. 43 is demonstration of application of fluidic diode concept indynamic sealing applications;

FIG. 44 shows details of various types of Fluidic Diode Seals (FDS),channels of which could be filled with liquid; and

FIG. 45 shows how FDS can be applied toward sealing of standalonecombustion chambers in various embodiments of HCCE.

DETAILED DESCRIPTION

Definitions. For purposes of this description and the claims of thisapplication, the following terms shall have the indicated meaningsunless the context clearly requires otherwise:

-   -   “Working medium” is a gaseous mixture that consists essentially        of air or includes a fuel/air mixture that is not capable of        auto-ignition.    -   “Recip-rotating” is a type of motion of a piston that includes        rotation of the piston alternately around two axes of rotation,        while simultaneously reciprocating as a whole.    -   “Sealing fluid” is a fluid that includes water, lubricating oil,        cooling liquid, refrigerant, or any other liquid suitable for        sealing purposes.    -   “Substantially isothermal compression (or expansion)” is the        process of compressing or expanding gas or gas/steam mixture        during which the temperature of the mixture remains        substantially constant.    -   “Piston's motion” is a motion of compressor's and the expander's        pistons, which, depending upon specific implementation, may        include complex motion, such as non-uniform rotation,        reciprocation, oscillation or recip-rotation.    -   “Combustion products (or by-products)” are products of        combustion of fuel, containing water vapor formed in a course of        combustion and, optionally, water vapor from the additionally        introduced water.    -   “Low pressure insertion mechanism” is a mechanism for        introducing water and/or fuel into the combustion chamber by        rotating a shaft containing cavities filled with a water and/or        fuel into the combustion chamber or, conversely, rotating the        combustion chamber into a stationary cavity filled with fuel        and/or water.    -   “Introduced water or fuel”—water or fuel injected or introduced        by means of the low-pressure insertion mechanism.    -   “Scissors” or “cat & mouse” is a piston configuration in which        piston rotating in one direction momentarily approaches another        piston rotating in the same sense and then retracts from this        second piston due to difference in angular speeds.    -   “PGM”—a Power Generating Module    -   “PCM”—a Power Conversion Module    -   “ERS”—an optional Energy Recovery System

“Fluidic Diode Seal” (“FDS”) is a seal formed between two bodies incollinear motion with respect to each other, when one or both of thesebodies have features that create locally high pressure for flow movingin one direction (leakage flow), such a feature would act as a dynamicseal with potential to substantially decrease or eliminate the leakage.

“Hybrid Cycle Combustion Engine” (“HCCE”) is an internal combustionengine implemented in accordance with various embodiments of theinvention and operating in accordance with a thermodynamic cycle diagramshown in FIG. 1.

Generalized Structure of an HCCE Engine in Accordance with EmbodimentsHerein

There are many different types of engines, operating in accordance withvarious thermodynamic cycles, and an even greater number ofmodifications within each type. These different types exist because eachoffers certain advantages over others. For example, while Diesel cycleengines are somewhat inferior in terms of efficiency to Otto cycleengines (which we sometimes call herein “four-stroke” engines, and thestrokes as “intake”, “compression”, “expansion”, and “exhaust”) whenboth operate at the same compression ratio, the Diesel engine normallyruns at higher compression ratios and it becomes more efficient than theOtto engine. Ericsson cycle engines as well as Stirling cycle enginesare superior to Otto cycle engines because they allow part of theexhaust energy to be recovered, but these engines are very cumbersome(and therefore expensive) to build and maintain. At the same time,Rankine cycle steam engines offer some advantages over internalcombustions engines, but are very large and slow.

A principal idea underpinning embodiments described in this applicationis a new, significantly improved thermodynamic cycle, referred to as the‘High Efficiency Hybrid Cycle’ (HEHC). This new cycle combines the bestfeatures of several known cycles. Several implementations of this newcycle are presented. Engines that implement this new cycle exhibithigher thermodynamic efficiency as well as mechanical efficiency (withoverall efficiency of 50%-60%), are economical to produce and maintain,and pollute less than engines utilizing other cycles.

The work performed, and, therefore, efficiency of a given cycle, isequal to the area delineated by a pressure/volume (PV) diagram. FIG. 1depicts a PV diagram for a typical Otto cycle, shown in dashed lines, aswell as for an engine using an HEHC, shown in solid lines. Thus toincrease efficiency, embodiments presented herein increase the area inthe PV diagram by “stretching” the delineating curves for the Ottocycle, which has some of the highest theoretical efficiencies. See, forexample, “Engineering Thermodynamics with Applications” by M. DavidBurghardt, p. 353, incorporated herein by reference. Referring to FIG.1, the Otto cycle starts at point 1, which is characterized by theintake volume V_(Intake) of the engine and ambient pressure ˜1 atm. Wenow identify features of the HEHC, which may be implemented to increasethe area defined by the PV diagram, and, therefore, the efficiency ofthe engine. Of course, implementing any one of these features willincrease efficiency; and implementing more of these features willfurther increase efficiency. In other words, not all features need beimplemented in order to realize some benefits of the embodimentsdescribed herein.

We will describe in more detail below engines that implement HEHC and wewill call such engines “Hybrid Cycle Combustion Engine”, or HCCE. Invarious exemplary embodiments, HCCE includes the following componentsdescribed throughout this description and depicted in the Figures.

COMPONENTS

-   100—PGM (Power Generation Module)-   110—compressor cover-   111—protrusion into compression chamber-   113—left valve housing (cylindrical openings)-   114—right valve housing (cylindrical openings)-   115—shaft housing (cylindrical openings)-   120—oscillating shaft-   121—compressor's piston-   122—expander's piston-   123—drive cam-   124—cam follower roller-   125—guide roller-   126—central drive shaft-   127—upper drive shaft-   128—lower drive shaft-   130—compressor body-   131—compression chamber-   132—compression chamber-   133—combustion chamber-   134—combustion chamber-   135—one-way air valve-   136—one-way air valve-   137—water injector-   140—separator-   141—air intake port-   142—air intake port-   143—exhaust port-   144—exhaust port-   145—air channel-   146—exhaust channel-   150—fresh air intake valve-   151—combustion products transfer valve-   152—channel-   153—left air/exhaust valve-   154—right air/exhaust valve-   155—shaft-   157—exhaust valve-   161—radial bearing-   162—radial bearing-   163—radial bearing-   164—radial bearing-   170—expander body-   171—expander chamber-   172—expander chamber-   180—expander cover-   181—protrusion into expansion chamber-   191—crankshaft-   192—magnets-   200—ERS (Energy Recovery System)-   300—PCM (Power Conversion Module)

HCCE Features

1. High compression ratio. In the Otto cycle (and other typical sparkignition engines), the air/fuel mixture is compressed but only topressure and temperature conditions that stop short of causingauto-ignition. Since compressing to a higher ratio can attain higherefficiency, the HCCE compresses air to a very high ratio, typicallyabove the pressure-temperature conditions that would cause auto-ignitionwere fuel present. However, the compression in various embodiments is ofair only (or working medium, as defined above), and fuel is added onlyafter the compression phase is substantially complete—as in theconventional Diesel cycle. However, in contrast to the approach ofDiesel cycle engines, in various HCCE embodiments, the fuel combusts atsubstantially constant volume conditions.

2. Near-isothermal compression. Isothermal compression requires lesswork for compression of a given amount of working medium to a givenpressure than adiabatic compression. Near-isothermal compression may beachieved by cooling the working medium during compression, e.g. byadding water during compression.

3. Constant-volume (isochoric) or decreasing-volume combustion. Ignitionstarts at point “2” in the PV diagram and proceeds to point “3”.Preferably, this should happen under isochoric conditions. In practicalOtto engines, this condition is not satisfied, because the piston, beingattached to a rotating crankshaft, travels a finite distance during thetime it takes the fuel to burn. To achieve a truly isochoric process, invarious HCCE embodiments, the piston will be momentarily stopped untilcombustion is substantially complete and/or the engine is configured toisolate the burning air/fuel mixture in a separate combustion chamber.

It is possible to further reduce the volume of the working medium by“moving” point 3 in the PV diagram “left” by adding a fluid medium, suchas water, during combustion. The water evaporates, reducing thetemperature within combustion chamber and therefore the pressure ofcombustion products. However, at the same time, water added in this wayreduces the volume occupied by combustion products within the combustionchamber, since evaporating water vapor occupies 1400 times the space ofliquid water. The volume decrease has an opposite effect on the pressureof combustion products—the volume decrease (in the absence of atemperature change) increases the pressure of combustion products.Therefore, while the net effect of the addition of liquid water into thecombustion chamber might be a slight decrease in the pressure at point3, the superheated steam generated during this process can be harnessedduring the next phase—expansion of the working medium, which now willcontain the products of combustion as well as this superheated, highpressure steam. Also, evaporating water cools the combustion chamber,which allows for the use of less expensive materials for engineconstruction. The reduced temperature also reduces formation ofundesirable NOx gases.

4. Increased pressure during the expansion stroke. In modern enginescylinder walls are cooled to prevent material degradation and melting.Cooling the cylinder walls lowers the curve between points “3” and “4”in the PV diagram—which has a negative effect on the total area underthe curve. In our case, the water evaporated during combustion helps tostretch the cycle curve upward. Additional water may be added todecrease wall temperature, while additional steam generated will be usedto perform more work.

5. Expanding to volume larger than intake volume. Point “4” in the PVdiagram shown in FIG. 1 can be shifted to the right by extending theexpansion stroke, that is, configuring the expansion stroke to provide avolume that is significantly larger than the volume provided during theintake stroke. This result may be accomplished by expanding combustionproducts (and steam) into an expansion chamber that has a larger volumethan the chamber used for the compression stroke. One way to implementsuch configuration is to utilize separate compression and expansionchambers and/or, if water is used, by adding a variable amount of liquid(water) in a compression and/or expansion chamber, so that more liquidis present during compression than during expansion.

6. Thermo-chemical recovery. Additional efficiency can be obtained bytransferring part of the heat from the exhaust gases back into thesystem, as is done in Stirling or Ericsson cycles. While technicallysuch heat transfer could be accomplished in Otto or Diesel engines byinstalling a simple heat exchanger, which would transfer the heat fromexhaust gases to incoming fresh air, practical considerations precludesuch a solution since the volume of such a “gas to gas” heat exchangerwould be excessively large, and hotter air temperatures wouldeffectively reduce power density of the engine. In our case we areforced to reduce the temperature of exhaust gases below 100 deg. C. torecover the water that we added during compression, combustion and/orexpansion strokes. However, instead of transferring heat to incomingair, we transfer this heat to gaseous fuel, as described in theinternational application No. PCT/US03/05749, mentioned above. Anadditional advantage of this approach is that the large amount of heatassociated with the change of phase of water between gaseous and liquidstates permits using water as a heat transfer medium in a heat exchangerthat occupies a volume comparable to the volume of a radiator used inmodern ICEs. In this embodiment, the heat recovered from the water maybe used to cause thermo-chemical decomposition of incoming gaseous fuelinto hydrogen and carbon monoxide, so that the resulting decomposed fuelhas a higher heat of combustion than before thermo-chemicaldecomposition.

In addition to enabling the hybrid cycle described above, it isdesirable for various embodiments of an engine in accordance with thepresent invention to have low friction between piston and cylinders aswell as a compact form-factor. In various embodiments, an engine inaccordance with the present invention may have features, discussed infurther detail below, including the following:

-   -   1. A compressor, which compresses air into one or more        combustion chambers, preferably during forward and return        strokes of operation, in such a way that while air is being        compressed on one side of the compressor's piston, fresh air is        inducted on the other side of the compressor's piston.    -   2. A set of one or more combustion chambers, for accepting hot,        pressurized air from the compressor. When fuel is introduced        into the combustion chambers, by means of a fuel introduction        mechanism, combustion begins and (optionally) continues until        complete combustion occurs.    -   3. A fuel introduction mechanism, which inserts the fuel into        the combustion chamber(s). This mechanism may inject fuel with        an injection pump, or may insert a low pressure gaseous fuel        into a high pressure combustion chamber by means of mechanical        insertion. When mechanical insertion is used, it may be        implemented in a number of configurations. One configuration        involves rotating a shaft located within the combustion chamber        in such a way that the cavity within the shaft that contains the        fuel is gradually rotated into the combustion chamber.        Conversely, another configuration involves rotating the        combustion chamber into a stationary cavity that is filled with        gaseous fuel. In another embodiment, any high-pressure fuel        injection mechanism may be used.    -   4. An optional water introduction mechanism, which can inject        liquid water with a water-injection pump, or insert liquid water        into the high pressure combustion chamber by means of mechanical        insertion. The mechanical insertion may be implemented just as        described with respect to the fuel introduction mechanism:        either by rotating a shaft located within the combustion chamber        in such a way that the cavity within the shaft that contains the        water is gradually rotated into the combustion chamber or,        conversely, the combustion chamber is rotated into the        stationary cavity that is filled with water. Also, in another        embodiment, the water may be injected or inserted into the        compressor and/or into the expander chambers for cooling        purposes.    -   5. An expander, which receives high-pressure, high-temperature        combustion products, and (optionally) high-pressure steam, from        the set of combustion chambers, and expands said combustion        products and steam, converting heat and potential energy into        work, preferably during forward and return strokes of operation,        in such a way that while combustion products and steam are being        expanded on one side of the expander's piston, the expended        combustion products and steam are exhausted on the other side of        the expander's piston. It is desirable that the expansion volume        of the expander be larger than the intake volume of the        compressor. This is easily implemented if the expander is a        separate volume from the compressor. In another embodiment, the        compressor itself may be used as the expander (i.e., one may use        the same volume for both compression and expansion, as is done        in a typical piston-based Otto or Diesel engine). Even if the        same volume is used, the expander may have larger gas expansion        volume than compression volume if more liquid is present in the        chamber during compression than during expansion.    -   6. An optional thermo-chemical recovery system in which water        contained in the exhaust is condensed and the energy recovered        from such a process is transferred to the fuel, in a process of        decomposing the fuel into a mixture of hydrogen and carbon        monoxide (and possibly some other gasses), having a heat of        combustion higher than that of original fuel.

It should be noted that while only a combination of all the featuresabove yields optimal efficiency, various embodiments of the inventionmight omit some of them. Numerous ways in which the above features maybe implemented are contemplated by the invention. Several exemplaryembodiments are discussed below.

In FIG. 2, we illustrate major modules an HCCE embodiment: a PowerGenerating Module (PGM), 100, a Power Conversion Module (PCM), 300, andoptional Energy Recovery System (ERS), 200, Data Acquisition and ControlModule (DAC), 400. ERS and DAC are disclosed in internationalapplication No. PCT/US03/05749 mentioned above and incorporated byreference.

Referring to FIG. 2, the pistons of the compressor and the expander mayexecute a complex motion, including motion that we have called“recip-rotating”. In general terms, in the “Definition” section, we havenot limited a “piston's motion” to reciprocation related to asubstantially uniform rotary motion of a connected output shaft. Withthese definitions in mind, the PCM 300 functions are to convert piston'smotion into output shaft motion or directly into electrical energy; tolimit the range of piston's motion in order to prevent the collisions ofpistons with walls of the engine; and, optionally, to smooth out powerfluctuations, by utilization of a flywheel.

There are many mechanisms, based on cams and non-circular gears thatallow those skilled in the art to implement simple and efficient PCMs.See for example, “Mechanism & Mechanical Devices Sourcebook” by NicholasP. Chironis, McGraw-Hill Companies, The—April 1991 ISBN 0-07-010918-4,pp. 71, 74 and 105, hereby incorporated herein by reference.

The PGM 100 of an HCCE in accordance with embodiments of the presentinvention may be implemented in a variety of ways, for example toproduce rotational, oscillatory or recip-rotating motion (examples willbe given later). If oscillatory motion is produced, it may be convertedinto rotary motion of an output shaft using the PCM 300. Conversion frompiston's motion into rotational motion of output shaft or directly intoelectrical energy by the PCM 300 will be described in detail below.

PGM—Liquid Piston

We will start with description of the PGM 100. In one embodiment, thePGM may be implemented using a liquid-piston concept shown in FIG. 3 anddescribed in the international application No. PCT/US03/05749 mentionedabove. We will to refer an ICE implementing the liquid-piston concept is“Fluid ICE™”.

The rigid metal piston of conventional ICEs is replaced with a liquidpiston, for example, a volume of water. The upper surface of water maynot be flat or even continuous during the motion of the liquid piston.The water surface substitutes for the upper surface of the metal piston.The table below summarizes the key differences in a 4 stroke engineusing a metal vs. liquid piston

Description of each stroke of a one cylinder, 2 valve ConventionalLiquid Piston based (air and exhaust), ICE Fluid ICE ™ Stroke 4 strokeengine Operation Operation 1. Intake with air valve piston moves liquidpiston moves open an down, driven by down, driven by the air/fuelmixture the crank shaft pump is sucked in 2. Compression with bothvalves piston moves liquid piston moves closed air/fuel up, driven byup, driven by the mixture is the crank shaft pump compressed 3.Expansion with both valves A spark plug is A spark plug is not closed anair/fuel required to ignite required for mixture combusts air/fuelmixture. combustion. A high creating very The piston gas temperatures,high pressure moves down, caused by high in the cylinder driven by thecompression ratio, high pressure. enable spontaneous The movingcombustion. The piston drives liquid piston moves the crank shaft downdriven by the high pressure. The water flow drives a hydraulic motor 4.Exhaust with exhaust piston moves liquid piston moves valve open a up,driven by up, driven by the combusted the crank shaft pump air/fuelmixture is expelled from the cylinder

We note the following characteristics of the ICE having a liquid piston:

The cylinders of conventional engines are round to facilitate sealingthe space between piston and cylinder walls. As FIG. 3 demonstrates, thecylinder cross-section of liquid based engine does not have to be roundas there is no sealing issue. The rectangular design facilitatesvolumetric efficiency (i.e. the same power in a smaller volume) and,more importantly, also enables a new design of intake and exhaustvalves. FIG. 6 shows, as an example, that one rotary valve can operateIntake and Exhaust valves—this simplifies the design considerably. Itshould be also noted that rotary valves operate much quieter and do notgenerate knocking noise of conventional poppet valves.

Water evaporates during piston expansion. This is beneficial to ICEbecause:

-   -   a. Evaporating water increases the pressure within the cylinder        during expansion, as was discussed above. This effectively means        that Fluid ICE is a synergetic combination of an internal        combustion engine and steam engine, except that there is no        boiler and the evaporation process is almost instantaneous.    -   b. The evaporating water carries a large amount of (latent) heat        of evaporation, which can potentially be used to do more work.        This is accomplished by sending hot exhausts, containing water        vapors, through an Energy Recovery System (ERS), shown in FIGS.        2 and 5 and explained later in this paper.    -   c. Water cools and lubricates the cylinder alleviating the need        for additional cooling and lubrication.

The volume of water in the cylinders is controlled by valves. In variousembodiments of the invention, this has a positive effect on thethermodynamic efficiency of the engine:

-   -   a. Air intake volume is smaller than exhaust volume at the end        of the expansion stroke. As shown in FIG. 1—this alone increases        thermodynamic efficiency by as much as 20%.    -   b. In a conventional engine, as soon as combustion begins, the        piston begins to expand, which cools the fuel/air mixture,        causing incomplete combustion. In Fluid ICE, combustion can        occur at a constant volume—a preferable condition that allows        for complete burning of fuel.

To accommodate very high water flows (small amounts but very highvelocity), standard, commercially available pump and hydraulic motorhave to be very large. Instead, we use vane-type actuators, whichsimultaneously serve as a pump and a hydraulic motor. These actuatorsare described in the section “Putting it all together”, below.

Energy Recovery System (ERS)

The ERS (FIG. 1) serves a plurality of purposes. It converts raw fuel,such as hydrocarbon gas (Natural Gas or vaporized liquid fuel) and watervapor into reformat gas, containing H2, CO and other gases which have upto 27% higher heat of combustion than raw fuel gas. The conversionoccurs in a thermo-chemical recuperator via endothermic,catalyst-assisted reactions occurring at a constant temperature between450 and 750 deg. C.. The required temperature for this process dependsupon the properties of the catalyst and amount of water vapor and/orcarbon dioxide. Exhausts supply the additional energy needed for thisconversion, thus this process significantly increases the efficiency ofthe engine's operation. The engine can run on raw fuel as well, so thesereforming components are optional. A comparison of energy distributionwithin conventional and Fluid ICE™ Engines is shown in FIG. 4. A moredetailed energy balance sheet for Fluid ICE™ engine is shown in FIG. 5.

A second purpose for ERS is water recovery. Because (evaporating) watermust not leave the system at a rate greater than the combustion processgenerates it, water must be recovered from the exhausts. The exhaustsmust be cooled to below 100 deg. C., as is effectively done when usedwith the ERS. The Thermo-chemical Recovery system was offered first forlarge power plants in “The Thermo-chemical Recovery System—Advanced HeatRecovery”, By D. K. Fleming and M. J. Khinkis, 12th Energy TechnologyConference and Exposition, Washington D.C. Mar. 25-27, 1985, as well asdescribed in U.S. Pat. Nos. 4,900,333; 5,501,162; and 5,595,059, allincorporated herein by reference, but was never applied to ICE becausesuch an energy recovery system would create additional, large andexpensive components handling water and water vapors. For Fluid ICE,these components are integral and synergetic.

Efficiency

The reasons for higher thermodynamic efficiencies of the Fluid ICEengine are shown in FIG. 1. The area delineated by solid lines 1→2→3→4represents the amount of energy that can be extracted during a singlecycle of the Fluid ICE engine. Calculations show that the theoreticalthermodynamic efficiency of Fluid ICE engine is 74%, whereas forconventional ICE it is only around 50-57%.

Putting it all Together

FIG. 3 shows both a perspective view and an exploded view of a 4cylinder, 4-stroke engine using a liquid piston as described. The liquidpiston engine's PGM, which transforms chemical energy of fuel intooscillatory shaft motion, is here implemented by four cylinders and twoactuators, located between the cylinders. An actuator is comprised of anoscillating vane and two volumes. The two volumes are always filled withwater. Thus, A-1 (actuator #1), is formed by the oscillating vane OV-1and volumes V1, adjacent to cylinder #1 and volume V2, adjacent tocylinder #2. Similarly, A-2 (actuator #2), is formed by the oscillatingvane OV-2 and volumes V3, adjacent to cylinder #3 and volume V4,adjacent to cylinder #4.

The vane can be driven by applying high-pressure water on one side, sothe vane acts as a hydraulic motor. Simultaneously, the other side ofthe vane pushes water out, so the vane is also acting as a pump. Thus,actuators are used to serve as both a hydraulic motor and pump.

Oscillating Vane #1 (OV-1) is shown in FIG. 6 between cylinders #1 and#2. The Oscillating Vane #2 (OV2) on the back of the engine is betweencylinders #3 and #4. Both vanes move together because they are rigidlyattached to the same shaft, which executes oscillating motion.

Assuming that shaft and both OV-1 and OV-2 are moving counterclockwise(as shown by the arrow in FIG. 6. The operation of Fluid ICE™ engine isas follows:

In cylinder 1:

The air valve opens the air intake port. The water valve opens to allowwater to flow between cylinder #1 and V1 (left hand side of A-1). AsOV-1 moves counterclockwise, water is pumped out of cylinder #1 and intothe V1 compartment of A-1. An air is drawn into the cylinder; thus,cylinder 1 is undergoing the intake phase.

In cylinder 2:

The water valve for cylinder #2 is open, so as OV-1 movescounterclockwise, water from V2 (the right compartment of A-1) is pumpedinto cylinder #2. The exhaust valve of cylinder #2 is open—allowingexhaust gasses to exit through the exhaust port. This means thatcylinder #2 is undergoing the exhaust phase.

In cylinder 3:

Assume that combustion has recently occurred in cylinder 3. Water fromcylinder #3, under pressure from expanding gasses, flows into V3. Theinflow of water into A-2 drives OV-2 (and correspondingly, OV-1) to movein a counterclockwise direction. Both Exhaust and Air ports of cylinder#3 are closed, as cylinder #3 is undergoing the expansion phase.

In cylinder 4:

Water is pumped by OV-2 from V4 into cylinder #4, both Exhaust and Airports of which are also closed. Thus, cylinder #4 undergoes thecompression phase.

Upon completion of these phases, the water valve for cylinder 4 closesand a fuel is introduced into this cylinder so it auto-ignites. After ashort delay, the water valve is reopened, and the pressure drives theOV-2. At this point, cylinder #1 undergoes compression, cylinder #2undergoes exhaust, cylinder #3 undergoes intake, and cylinder #4undergoes expansion. The descriptions for each stroke are the same asabove, the only difference being which cylinder is in a given stroke.The process continues, and each cylinder undergoes the intake,compression, combustion/expansion, and exhaust strokes in turn. The netresult of this system is an oscillating shaft, driven by A-1 or A-2. Tobe useful for generating rotational motion, an Oscillatory-to-Rotary(O-2-R) converter is used as will be described later in thisapplication.

Implementation of Liquid Piston Engine Using Separated Compression andExpansion Chambers

Separated compression and expansion chambers' is a modification of theengine design discussed above. It is also based on a liquid pistondesign, but employs separated compression and expansion chambers. Thisdesign employs two combustion chambers located within two intake/exhaustvalves. The construction of this engine is similar to the 4-valve liquidpiston based ICE, shown in FIGS. 3 and 6, with the main exceptions beingthat there are no water valves and the air/exhaust valves are combinedwith the combustion chamber. The resulting design is shown in FIGS. 7 to11.

FIG. 7 presents an exploded view of the Power Generation Module (PGM) ofa 4-stroke HCCE engine, while FIG. 8 shows specific details ofcomponents. Further description will refer, unless otherwise indicated,to FIG. 7 and FIG. 8. In various embodiments, PGM 100 of this engineincludes

-   -   a. an engine body that includes the compressor body 130, a        separator 140, and the expander body 170;    -   b. a compression piston 121—a solid body, surrounded in whole or        in part by liquid (water, in simplest case), see FIG. 10. The        piston 121, separates air cavity into compression chamber 131,        and compression chamber 132, and moves in oscillatory motion        between these compression chambers;    -   c. an expansion piston 122—a solid body, surrounded in whole or        in part by liquid. The piston 122 separates exhaust cavity into        expander chamber 171 and expander chamber 172, and moves in        oscillatory motion within this expansion cavity.    -   d. oscillating shaft, 120 which mechanically couples compression        piston 121 to expansion piston 122;    -   e. two air/exhaust valves: left valve 153 and right valve 154.        Each valve contains an air channel, which allows fresh air to        enter the compression chamber and/or exhaust channel, which        allows combustion products to exit the expansion chamber. Each        valve also contains combustion chambers 133, 134,        correspondingly). Left and right valves are mirror images of        each other and, during the operation, rotate in opposite        directions. The details of the right valve are shown in FIG. 9;    -   f. two compression chambers 131 and 132, each of which is formed        by the space between the compressor body 130, compression piston        121, and either the body of the valve 153,154, or body of        combustion chamber 133/134, or both; and    -   g. two expansion chambers 171 and 172, each of which is formed        by the space between the expander body 170, expansion piston        122, and either the body of the valves 153, 154 or body of        combustion chamber 133,134, or both.    -   h. Covers, bearings and bolts are not shown;

Liquid (water) partially fills each compression and/or expansionchamber. The surface of the liquid exposed to air or exhausts representsa Liquid Piston (FIG. 10).

The compressor volume, which is the sum of the volumes of compressionchambers 131 and 132, denoted V₁₃₁+V₁₃₂, is separate from expansionvolume, V₁₇₁+V₁₇₂; expansion volume is larger than compression volume,in our case 2.5 times. Depending upon the position of the compressionpiston 121, the volumes of compression chambers V₁₃₁ and V₁₃₂ vary fromV_(Intake), maximum volume during initial phase of intake stroke, tozero at the end of intake stroke. The volumes of compression chambers131 and 132 are complementary, i.e., V₁₃₁+V₁₃₂=V_(Intake).

Similarly, depending upon position of expansion piston 122, the volumesof expansion chambers V₁₇₁ and V₁₇₂ vary from V_(Exhaust), duringinitial phase of exhaust stroke to zero. The volumes of expansionchambers 171 and 172 are complementary, i.e., V₁₇₁+V₁₇₂=V_(Exhaust).

Operation

The expansion piston 122, driven by combustion products, expanding inexpansion chamber 171 (acting as a hydraulic motor), rotates oscillatingshaft, 120. Simultaneously, 122 exhausts from expansion chamber 172already expanded combustion products, (expander's piston 122, pusheswater out, acting as a pump). Thus, expander's piston 122 is used toserve as both a hydraulic motor and pump. At the same time, thecompression piston 121, driven by the oscillating shaft 120, compressesfresh air in compression chamber 132, while inducting air intocompression chamber 131, in both cases compressor's piston 121, isacting as a pump. Oscillating shaft 120, is driven by expansion piston122, in the beginning of expansion stroke and by a flywheel (not shown)which could be attached either to oscillating shaft 120, or to theoutput shaft of PCM.

To further explain the operation of the engine, it is necessary toconduct a closer examination of operation of valves. Since valveoperation in many instances is similar in various engine designs andwith the purpose of conserving space, we will refer to FIG. 22, forpositioning of pistons and valves, in spite of the fact that this Figurerelates to a different engine design. The operation of the engine is asfollows:

Position 1

Both pistons 121 and 122 are in extreme left positions, starting torotate clockwise. V₁₃₁=0, V₁₃₂=V_(Intake), V₁₇₁=0, V₁₇₂=V_(Exhaust);

The left air/exhaust valve 153 is stationary and in such position thatthe air intake port of compressor chamber 131 is open. Fresh air will beinducted into the compressor chamber 131 when the compression piston,121 will start moving, thus, the compressor chamber 131 will begin theintake stroke.

The exhaust port of expander chamber 132 is closed. Combustion has justbeen completed and combustion chamber volume is connected to expansionchamber 171. Combustion products will be expanding into the expansionchamber 171 when the expansion piston 122 starts moving, thus, thevolume 171 will begin the expansion stroke.

The left air/exhaust valve 153 is stationary and in such position thatthe air intake port of compressor chamber 132 is closed. The air,already contained in the compressor chamber 132, will be compressed whenthe compression piston 121 starts moving, thus, the compressor chamber132 will start the compression stroke.

The exhaust port of compressor chamber 132 is open. Already expandedcombustion products will be exhausted from expansion chamber 172 whenthe expansion piston 122, starts moving, thus, expansion chamber 172will start the exhaust stroke.

Position 2

Both pistons 121 and 122, have just arrived to their extreme rightpositions. V₁₃₁=V_(Intake), V₁₃₂=0, V₁₇₁=0, V₁₇₂=V_(Exhaust);

Both valves are stationary and in the same position as above.

-   -   compression chamber 131 has completed the intake stroke, and        pressure therein is close to ambient.    -   expansion chamber 171 has completed the expansion stroke.        Pressure in the combustion chamber of left valve, 153, and        expansion chamber 171 is close to ambient.    -   expansion chamber 172 has completed the exhaust stroke. There        are no exhausts in expansion chamber 172, as its volume is zero.    -   compression chamber 132 has completed the compression stroke.        There is no air in compression chamber 132, as its volume is        zero. Hot compressed air is in the compression chamber within        the right valve 154.        Position 3

Both pistons 121 and 122 are momentarily stationary, in extreme rightposition. V₁₃₁=V_(Intake), V₁₃₂=0, V₁₇₁=0, V₁₇₂=V_(Exhaust);

The left air/exhaust valve 153 is rotated 180 degrees. In the process ofrotation the following occurs: combustion chamber begins exposed toambient air. At the end of 180 degrees rotation it is disconnected fromthe ambient air and aligned with compression chamber 131. It is readyfor compression stroke. At the end of 180 degrees rotation, the exhaustchannel is aligned with expansion chamber 171 and is ready for exhauststroke.

The right air/exhaust valve 154 is rotated 180 degrees. In the processof rotation the following occurs: combustion chamber 134 passes througha cavity within the compressor body, 130, which contains gaseous fuelunder low pressure. Hot, due to compression, air is mixed with thegaseous fuel and because its temperature is above the auto-ignitiontemperature of the fuel, a spontaneous combustion occurs. Optionally,water could be inserted into combustion chamber (before, during or afterignition). Rotation of air/exhaust valve takes sufficiently long timefor combustion to complete. At the end of rotation, the combustionchamber 134 is connected to expansion chamber 172, while air port on 132opens (i.e. compression chamber 132 is exposed to ambient air).Expansion chamber 172 is ready to start expansion stroke, whilecompression chamber 132 is ready to start intake stroke.

Position 4

Both pistons 121 and 122 are in extreme left position, starting torotate counterclockwise. V₁₃₁=0, V₁₃₂=V_(Intake), V₁₇₁=0,V₁₇₂=V_(Exhaust);

Both valves are stationary and in the same position as above.

-   -   compression chamber 131 has completed the compression stroke.        There is no air in compression chamber 131, as its volume is        zero. Hot compressed air is in the compression chamber within        the left valve 153.    -   expansion chamber 171 has completed the exhaust stroke. There        are no exhausts in expansion chamber 171 as its volume is zero.    -   compression chamber 132 has completed the intake stroke, and        pressure therein is close to ambient.    -   expansion chamber 171 has completed the expansion stroke.        Pressure in the combustion chamber 133, of left valve 153, and        expansion chamber 171 is close to ambient.        Transition from Position 4 to Position 1

Both pistons 121 and 122 are momentarily stationary, in extreme leftposition. V₁₃₁=0, V₁₃₂=V_(Intake), V₁₇₁=0, V₁₇₂=V_(Exhaust);

The left Air/Exhaust valve 153, is rotated 180 degrees. In the processof rotation the following occurs: combustion chamber 133, passes throughthe cavity within the body, B, which contains gaseous fuel under lowpressure. Hot, due to compression, air is mixed with the gaseous fueland because its temperature is above the auto-ignition temperature ofthe fuel, a spontaneous combustion occurs. Optionally, water could beinserted into combustion chamber (before, during or after ignition).Rotation of air/exhaust valve takes sufficiently long time for acomplete combustion to occur. At the end of rotation, the combustionchamber 133, is connected to expansion chamber 171, while air port oncompression chamber 131 opens (i.e. compression chamber 131 is exposedto ambient air). Expansion chamber 171 is ready to start expansionstroke, while 131 is ready to start intake stroke.

The right air/exhaust valve 154 is rotated 180 degrees. In the processof rotation the following occurs: combustion chamber begins exposed toambient air. At the end of 180 degrees rotation it is disconnected fromthe ambient air and aligned with compression chamber 132. It is readyfor compression stroke. At the end of 180 degrees rotation, the exhaustchannel is aligned with expansion chamber 172 and is ready for exhauststroke. Note that combustion, and therefore expansion, occurs on everyswing of the oscillating shaft 120.

Implementations of HCCE described above results in the followingbenefits:

-   -   compressing air, rather than air/fuel mixture, allows for a very        high compression ratio (15 to 30+). Fuel is introduced        separately into the combustion chamber;    -   optionally injecting water into a compression chamber during the        compression stroke lowers the work required to compress the air        and brings the process closer to isothermal compression;    -   a separate, constant volume combustion chamber allows for        isochoric combustion. If water is added to the combustion        chamber before combustion is complete, then, combustion will        occur under the condition of reduced volume (due to evaporating        water), which is even more efficient than isochoric combustion.        This water also lowers the temperature of gases in the        combustion chamber, which lowers the emission levels of NOx, and        allows for lower grade materials that could be used for        construction of the engine;    -   there is additional pressure during expansion, due to steam        formed during the combustion and expansion processes; and    -   exhaust pressure is low because the expansion volume is larger,        2 to 5 times than the intake volume, which is easily        accomplished because the expander is separate from the        compressor.    -   Energy Recovery System can be implemented as described herein

Modifications

To conserve on amount of liquid needed for proper operation of thisengine as well as total volume of the engine, it is possible to usemodification shown on FIG. 11. Also, various other shapes and forms ofcombustion chamber, expansion chamber, valves, pistons (for example,pistons 121,122 may have different shapes from each other), etc. arepossible, which do not change the spirit of the invention.

Oscillating Piston, V-Configuration

The embodiments shown in FIGS. 12-20 may be implemented with or withoutwater. FIG. 15 presents an exploded view of a 4 cylinder, 4-stroke HCCEengine. Shown in FIGS. 16 and 17 are the details of some components,which are important for understanding the engine's operation. Furtherdescription will refer, unless otherwise indicated, to FIG. 17. In thisengine the expander volume (V_(C3)+V_(C4)) is separate from, and largerthan, the compressor volume (V₁₃₁+V₁₃₂).

Referring to FIGS. 14 and 15, in one embodiment, PGM 100 includes:

-   -   The engine body including the compressor body 130, a separator        140, and the expander body 170;    -   compression piston 121—a solid body, optionally surrounded in        whole or in part by liquid (water, in a particular embodiment).        The piston 121, separates air cavity into compression chamber        131 and compression chamber 132, and moves in oscillating motion        within air cavity;    -   expansion piston 122—a solid body, optionally surrounded in        whole or in part by liquid. The piston 122, separates exhaust        cavity expander chamber 171, and expander chamber 172, and moves        in oscillating motion within the exhaust cavity;    -   oscillating shaft 120, which mechanically couples piston 121 to        piston 122;    -   Two air/exhaust valves: left valve 153 and right valve 154. Each        valve contains an air channel 145, which allows fresh air to        enter the compression chamber and/or exhaust channel 146, which        allows combustion products to exit the expansion chamber. Each        valve also contains a combustion chamber (133 and 134,        correspondingly). Left and right valves are mirror images of        each other and, during the operation, rotate in opposite        directions. The details of the left valve are shown in FIG. 9;    -   Two compression chambers 131 and 132, each of which is formed by        the space between the compressor body 130, compression piston        121, and either the body of the valve 153/154 or body of        combustion chamber 133/134, or both;    -   Two expansion chambers 171 and 172, each of which is formed by        the space between the expander body 170, expansion piston 122,        and either the body of the valve 153/154 or body of combustion        chambers 133,134), or both;    -   Covers 180 and 110, held to body with bolts 151;    -   The engine body (130,140,170), FIGS. 14 and 16, is a solid part        with a number of features: compression chamber 131, compression        chamber 132; two cylindrical openings (113 and 114) for left and        right air/exhaust valves; cylindrical opening (115) for shaft        (120); two air intake ports (141) and (142), two exhaust ports        (143) and (144), and optional fuel and water channels (not        shown) located inside of 113 and 114 within the body of the        engine.    -   compression piston 121 moves within air compressor cavity, as        shown in FIG. 18, while exhaust piston 122 moves within exhaust        expansion cavity. Both pistons are coupled via the oscillating        shaft 120 and, therefore, move synchronously together.    -   Oscillating shaft 120, FIG. 15, has spline, which matches groves        on the compression piston 121 and exhaust piston 122, as well as        another spline which allows coupling to PCM (300).    -   Valve (154) is a mirror image of valve (153), FIG. 15, is a        cylindrical body with air channel (145), exhaust channel (146)        and combustion chamber cavity (133 or 134).

Depending upon the position of the compression piston 121, the volumesof compression chambers V₁₃₁ and V₁₃₂ vary from V_(Intake), maximalvolume during initial phase of intake stroke, to zero at the end ofintake stroke. The volumes of compression chambers 131 and 132 arecomplementary, i.e., V₁₃₁+V₁₃₂=V_(intake). Similarly, depending uponposition of expansion piston 122, the volumes of expansion chambers V₁₇₁and V₁₇₂ vary from V_(Exhaust), during initial phase of Exhaust stroke,to zero. The volumes of expansion chambers 171 and 172 arecomplementary, i.e., V₁₇₁+V₁₇₂=V_(Exhaust).

Operation

The expansion piston 122 driven by combustion products, expanding inexpansion chamber 171, rotates oscillating shaft 120. Simultaneously,expansion piston 122 exhausts from expansion chamber 172 alreadyexpanded combustion products. At the same time, the compression piston121, driven by the oscillating shaft 120, compresses fresh air incompression chamber 132, while inducting air into compression chamber131.

Referring to FIG. 18, the operation of the engine is as follows:

Position 1

Both pistons, compression piston 121, and expansion piston 122, are inextreme left position, starting to rotate clockwise. V₁₃₁=0,V₁₃₂=V_(intake), V₁₇₁=0, V₁₇₂=V_(Exhaust);

The left air/exhaust valve 153 is stationary and in such position thatair intake port of compression chamber 131 is open. Fresh air will beinducted into compression chamber 131 when the compression piston 121,will start moving, thus, compression chamber 131 will begin the intakestroke.

The exhaust port of compression chamber 132 is closed. Combustion hasjust been completed and combustion chamber volume is connected toexpansion chamber 171. Combustion products will be expanding intoexpansion chamber 171 when the expansion piston 122 starts moving, thus,expansion chamber 171 will begin the expansion stroke.

The right air/exhaust valve 154 is stationary and in such position thatair intake port of compressor chamber 132 is closed. The air, alreadycontained in the compression chamber 132, will be compressed when thecompression piston 121 starts moving, thus, the compression chamber 132will start the compression stroke.

The exhaust port of compression chamber 132 is open. Already expandedcombustion products will be exhausted from expansion chamber 172 whenthe expansion piston 122, starts moving, thus, expansion chamber 172will start the exhaust stroke.

Position 2

Both pistons 121 and 122, have just arrived to their extreme rightpositions. V₁₃₁=V_(Intake), V₁₃₂=0, V₁₇₁=0, V₁₇₂=V_(Exhaust);

Both valves are stationary and in the same position as above.

-   -   compression chamber 131 has completed the intake stroke.        Pressure in the 131 is close to ambient.    -   expansion chambers 171 has completed the expansion stroke.        Pressure in the combustion chamber of left valve, 153, and        expansion chamber 171 is close to ambient.    -   expansion chambers 172 has completed the exhaust stroke. There        are no exhausts in 172, as its volume is zero.    -   compression chamber 132 has completed the compression stroke.        There is no air in 132, as its volume is zero. Hot compressed        air is in the compression chamber within the right valve, 154.        Position 3

Both pistons, compression piston 121, and expansion piston 122, aremomentarily stationary, in extreme right position. V₁₃₁=V_(Intake),V₁₃₂=0, V₁₇₁=0, V₁₇₂=V_(Exhaust);

The left air/exhaust valve, 153, is rotated 180 degrees. In the processof rotation the following occurs: combustion chamber begins exposed toambient air. At the end of 180 degrees rotation it is disconnected fromthe ambient air and aligned with 131. It is ready for compressionstroke. At the end of 180 degrees rotation the Exhaust channel isaligned with 171 and is ready for exhaust stroke.

The right air/exhaust valve 154, is rotated 180 degrees. In the processof rotation the following occurs: combustion chamber passes through acavity (not shown) within the compressor body 130, which containsgaseous fuel under low pressure. Hot, due to compression, air is mixedwith the gaseous fuel and because its temperature is above theauto-ignition temperature of the fuel, a spontaneous combustion occurs.Optionally, water could be inserted into combustion chamber (before,during or after ignition). Rotation of air/exhaust valve takessufficiently long time for a complete combustion to occur. At the end ofrotation, the combustion chamber is connected to expander chamber 172while air port on compression chamber 132, opens (i.e. compressionchamber is exposed to ambient air). Expander chamber 172, is ready tostart expansion stroke, while compression chamber 132 is ready to startintake stroke.

Position 4

Both pistons, compression piston 121 and expansion piston 122, are inextreme left position, starting to rotate counterclockwise. V₁₃₁=0,V₁₃₂=V_(Intake), V₁₇₁=0, V₁₇₂=V_(Exhaust); Both valves are stationaryand in the same position as above.

-   -   compression chamber 131 has completed the compression stroke.        There is no air in 132, as its volume is zero. Hot compressed        air is in the compression chamber within the left valve, 153.    -   expansion chamber 171 has completed the exhaust stroke. There        are no exhausts in 171, as its volume is zero.    -   compression chamber 132 has completed the intake stroke.        Pressure in 132 is close to ambient.    -   expansion chamber 171 has completed the expansion stroke.        Pressure in the combustion chamber of left valve, 153, and        expansion chamber 171 is close to ambient.        Transition from Position 4 to Position 1

Both pistons, compression piston 121, and expansion piston 122, aremomentarily stationary, in extreme left position. V₁₃₁=0,V₁₃₂=V_(Intake), V₁₇₁=0, V₁₇₂=V_(Exhaust); The left air/exhaust valve,153, is rotated 180 degrees. In the process of rotation the followingoccurs:

Combustion chamber passes through the cavity within the body, 130, whichcontains gaseous fuel under low pressure. Hot, due to compression, airis mixed with the gaseous fuel and because its temperature is above theauto-ignition temperature of the fuel, a spontaneous combustion occurs.Optionally, water could be inserted into combustion chamber (before,during or after ignition). Rotation of air/exhaust valve takessufficiently long time for a complete combustion to occur. At the end ofrotation, the combustion chamber is connected to expansion chamber 171,while air port on compression chamber 131 opens (i.e. compressionchamber 131 is exposed to ambient air). Expansion chamber 171 is readyto start expansion stroke, while compression chamber 131 is ready tostart intake stroke.

The right air/exhaust valve, 154, is rotated 180 degrees. In the processof rotation the following occurs: combustion chamber is being exposed toambient air. At the end of 180 degrees rotation it is disconnected fromthe ambient air and aligned with 132. It is ready for compressionstroke. At the end of 180 degrees rotation, the exhaust channel isaligned with expansion chamber 172 and is ready for exhaust stroke. Notethat combustion, and therefore expansion, occurs on every swing of theoscillating shaft 120.

Implementations of HCCE described above results in the followingbenefits:

-   -   Compressing air, rather than air/fuel mixture, allows for a very        high compression ratio (15 to 30+). Fuel is introduced        separately into the combustion chamber.    -   Optionally injecting water into a compression chamber (131 or        132) during the compression stroke lowers the work required to        compress the air and brings the process closer to isothermal        compression.    -   A separate, constant volume combustion chamber allows for        isochoric combustion. If water is added to the combustion        chamber before combustion is complete, then, combustion will        occur under the condition of reduced volume (due to evaporating        water), which is even more efficient than isochoric combustion.        This water also lowers the temperature of gases in the        combustion chamber, which lowers the emission levels of NOx, and        allows for lower grade materials that could be used for        construction of the engine.    -   There is additional pressure during expansion, due to steam        formed during the combustion and expansion processes.    -   Exhaust pressure is low because the expansion volume is larger,        2 to 5 times than the intake volume, which is easily        accomplished because the expander is separate from the        compressor.    -   Energy Recovery System can be implemented as described herein

Modifications

The engine described above, may have numerous implementations as well.Some of them obvious, such as various other shapes and forms ofcombustion chamber (i.e. close to semi-spherical, which decreases thesurface to volume ratio, which in turn reduces heat losses fromcombustion chamber), expansion chamber, valves, pistons (121 shape doesnot has to be the same as 122 shape), etc., which do not change thespirit of the design. For example, the piston angular travel may changein wide range, as could be seen from FIG. 19. Having both valves inclose proximity to each other could simplify the implementation of PCM,as they rotate in opposite sense to each other. Therefore, connectingboth valves via a gear pair of equal diameter, would allow one to applythe required motion to one valve only—the second one will automaticallyrotate in opposite sense. In addition, such geometry would allow havinghigher power density.

Another important variation is shown on FIG. 20. Both pistons could havelarge internal diameter space in the middle, which could be used forimplementation of PCM. Such a combination would yield an engine ofsmaller size and, therefore, will increase power density even higher.

Other implementations may have some subtle design features that might beuseful in building a commercial engine. One such a specificimplementation will be discussed below.

Large Angle Oscillating Piston Design

FIG. 21 through 26 show another implementation of an HCCE engine, whichis described below. The engine features a slightly different arrangementof valves and combustion chambers compared to other engines describedthus far.

Referring to FIGS. 1 and 24, in one embodiment, PGM, 100 of this engineincludes:

-   -   Compressor body, 130, which contains combustion chambers 133 and        134, FIGS. 24 and 34 a), and one way air valves (ball, poppet,        fluidic, etc.) 135 and 136, allowing airflow from the        compression chambers, 131 and 132, into combustion chambers, 133        and 134, correspondingly. It may also contain special passages        that could deliver gaseous or liquid fuel and/or liquid water        directly into combustion chambers, or, preferably, into        combustion products transfer valve 151.    -   Expander body, 170;    -   Separator, 140;    -   Compressor cover, 110;    -   Expander cover, 180, which also houses PCM;    -   Two compression chambers, 131 and 132, formed by space between        compressor body, 130, compressor's Piston 121, separator, 140,        and compressor cover, 110;    -   Two expander chambers, 171 and 172, formed by space between        expander body, 170, expander's Piston 122, separator, 140, and        expander cover, 180;    -   A compressor piston 121, a solid body, or, optionally, a solid        body surrounded in a part by a liquid; the said compressor        piston 121, moves within compressor body and separates two        combustion chambers. It oscillates around axis of oscillating        shaft;    -   An expander piston 122, coaxial to compressor piston 121, a        solid body, or, optionally, a solid body surrounded in part by a        liquid; the said expander piston 122, moves within expander body        and separates two expansion chambers. It oscillates around axis        of oscillating shaft synchronously with compressor piston and        oscillating shaft;    -   Oscillating shaft (120) which couples mechanically compressor's        piston 121, and expander's piston 122. It may have a spline,        which matches groves on the compressor piston (121) and exhaust        piston (122), as well as another spline which allows coupling to        PCM (300). Alternatively, it could be made as one whole with        either pistons;    -   Combustion products transfer valve 151, which has two channels,        152 and 153, allowing combustion chamber space 133 to be        connected with expander chamber 171 via channel 152, or        combustion chamber space 134 to be connected with expander        chamber 172, via channel, 153;    -   Exhaust valve 157, allowing already expanded gasses to exhaust        into the environment or ERS.    -   Shaft 155, which connects valves 151 and 157. It is driven        intermittingly back and forth, while compressor and expander        pistons are stationary;    -   Fresh air intake valve, 150, which allows fresh air to be        inducted into compression chambers during intake stroke. This        could be substituted with one way valves—ball, poppet, fluidic        types, etc.    -   Liquid (water) partially or completely filling channels 152 and        153;    -   Radial bearings, 161, 162, 163 and 164, which hold rotationally        shafts 120 and 155;

Depending upon position of compression piston 121, the volume ofcompression chambers V₁₃₁ and V₁₃₂ varies from V_(Intake), duringinitial phase of intake stroke, to zero at the end of intake stroke. Thevolumes of compression chambers V₁₃₁ and V₁₃₂ are complementary in asense that V₁₃₁+V₁₃₂=V_(Intake).

Similarly, depending upon position of expansion piston 122, the volumeof expansion chambers V₁₇₁ and V₁₇₂ varies from V_(Exhaust), duringinitial phase of Exhaust stroke, to zero. The volumes of expansionchambers V₁₇₁ and V₁₇₂ are complementary in a sense thatV₁₇₁+V₁₇₂=V_(Exhaust).

It should be noted that V_(Exhaust) to V_(Intake) ratio, adjustable byshape and/or thickness of the compressor's piston 121, and expander'spiston 122, could be selected in a such a way that the pressure ofexpanded combustion products at the end of the expansion stroke is closeto atmospheric.

Operation

We start the description of engine operation in the position where theexpander's piston 122, moves clockwise (FIG. 25d ) driven by pressurefrom the combustion products, expanding into expansion chamber 171 fromthe combustion chamber 133. The combustion products transfer valve 151has channel 152 aligned with combustion chamber 133 (FIG. 25b )),allowing combustion products into expansion chamber 171 (FIG. 25d )).

At the same time, expander's piston 122, pushes the already expandedgasses out of chamber 172, through a channel in exhaust valve 157, whichis synchronized with combustion products transfer valve 151.

Compressor's piston 121, (FIGS. 25 a) and b)), moves in the samedirection, clockwise, because it is mechanically coupled with expander'spiston 122. In doing so, it is compressing the air located in thecompression chamber 132, and inducting ambient air into compressionchamber 131. Compressed air within compression chamber 132, entersthrough the one-way air valve 136, (FIG. 24) into combustion chamber134.

Thus four chambers of engine are undergoing four different strokes:

Compression chamber 131—intake stroke;

Compression chamber 132—compression stroke;

Expander chamber 171—expansion stroke;

Expander chamber 172—exhaust stroke.

These strokes will be completed when both pistons simultaneously reachtheir end points at full clockwise position. The degree of angularrotation of the pistons is controlled by the PCM—to prevent pistons fromcolliding with walls of compressor and expander.

In this position (FIG. 26), combustion products transfer valve 151, isstill located over combustion chamber 133. Combustion chamber 134 isclosed by the combustion products transfer valve, 151, body, whilechannel 153, is in position over the water injector, 137, and fuelinjector (not shown, for clarity). Since channel 153, is underatmospheric pressure, as will be understood later, the water togetherwith gaseous fuel fills in channel 152. Both water and gaseous fuelcould be under small pressure. Optionally, channel 153, just likechannel 152, could be made of more complex, 2-chamber shape, so thatgaseous fuel and water do not have to mix together.

As stated above, both, compressor's piston 121, and expander's piston122, will become stationary at the end of their stroke. At this time:

-   -   The combustion chamber 134, contains hot pressurized air. Since        only fresh air is compressed, rather then air/fuel mixture, we        can compress it to high compression ratio of 15 to 30 or above,        which will bring the temperature of air significantly above the        auto ignition point.    -   The combustion chamber 133, together with expander chamber 171,        now contains completely expanded gases, since they are both        connected through channel 152. The expansion is carried to ˜        atmospheric pressure.    -   The compression chamber 131 is now filled in with fresh air.    -   The compression chamber 132 is at zero volume now, just like        expander chamber 172.

While the compressor's piston 121, and the expander's piston 122, arestationary in this extreme right position (FIG. 26), valves 151 and 157,driven by the shaft, 155, rotate counter-clockwise until channel 153,matches the opening of combustion chamber 134, as shown in FIG. 26a ).

In the course of rotation, the combustion products transfer valve 151,turns counterclockwise and exposes the fuel contained in channel 153, tothe hot pressurized gasses within combustion chamber 134. Spontaneouscombustion begins and continues for as long as it takes for fuel tocomplete combustion process. At this time:

-   -   The combustion chamber 134, contains very hot, very high        pressure combustion products. In spite of the fact that channel        153, is lined up with opening from combustion chamber 134,        gasses can't escape from combustion chamber 134, since water        contained within channel 153, and expander's piston 122, are        blocking the exit.    -   As above, the combustion chamber 133, together with expander        chamber 171, contains completely expanded gases. Now, however,        they are not connected to each other, since channel 152 is not        lined up with combustion chamber 133. The expander chamber 171,        is connected with ambient air through the hole in exhaust valve        157.    -   As above, the compression chamber 131, is filled in with fresh        air.    -   As above, the compression chamber 132, and expander chamber 172        are at zero volume.

After combustion is complete, which could last as long as 10-20 deg ormore of PCM shaft rotation, both compressor's piston 121, and expander'spiston 122, start counterclockwise rotation until they reach theirextreme left positions, at which moment they pause, until valves 151 and157 are rotated clockwise and the whole sequence repeats. As in otherdesigns discussed so far, combustion, and therefore expansion, occurs onevery swing of the oscillating shaft 120.

Implementations of HCCE described above results in the followingbenefits:

-   -   Compressing air, rather than air/fuel mixture, allows for a very        high compression ratio (15 to 30+). Fuel is introduced        separately into the combustion chamber.    -   Optionally injecting water into a compression chamber (131 or        132) during the compression stroke lowers the work required to        compress the air and brings the process closer to isothermal        compression.    -   A separate, constant volume combustion chamber allows for        isochoric combustion. If water is added to the combustion        chamber before combustion is complete, then, combustion will        occur under the condition of reduced volume (due to evaporating        water), which is even more efficient than isochoric combustion.        This water also lowers the temperature of gases in the        combustion chamber, which lowers the emission levels of NOx, and        allows for lower grade materials that could be used for        construction of the engine.    -   There is additional pressure during expansion, due to steam        formed during the combustion and expansion processes.    -   Exhaust pressure is low because the expansion volume is larger,        2 to 5 times than the intake volume, which is easily        accomplished because the expander is separate from the        compressor.    -   Energy Recovery System can be implemented as described herein

Modifications

The engine described above, may have numerous implementations as well.Some of them obvious, such as various other shapes and forms ofcombustion chamber, expansion chamber, valves, pistons, etc., which donot change the spirit of the design. For example, it is possible to makevalves rotate in a continuous rather then oscillatory manner.

Also, of particular interest may be design shown in FIG. 27. In thisdesign compressor's piston 121, and expander's piston 122, are locatedon an oscillating disc rather than on the oscillating shaft, as in aprevious designs. The details of valves and combustion chambers are notshown in significant details in this example, as they could take variousforms: stationary or oscillating or continuously rotating combustionchamber(s) and or valve(s); combustion chambers and valves could be oneor two or more separate parts, etc. They could also move in thedirection perpendicular to piston's plane in a reciprocating motion oreven in reciprocating and rotary motions simultaneously. The same istrue for all other designs we are discussing in this patent. The largeinternal diameter allows placement of PCM inside this central volume.

Constant Width Piston Design

A preferred implementation of HCCE engine is shown in FIG. 28 through33. It is based on a (modified) Reuleaux triangle shaped piston, similarto what is used in a Wankel (rotary) engine, so it bears certainsimilarity to it, but it is built on the design objectives outlined insection “Generalized Structure of an HCCE Engine” above and, therefore,operates on a different thermodynamic cycle and different mechanicalprinciple.

Referring to FIGS. 28 and 29, in one embodiment, PGM 100 of the engineincludes:

-   -   Compressor body 130, which houses combustion chambers 133 and        134, compressor's piston 121, and drive shafts 127, and 128. It        has, optionally, air intake ports 141 and 142 (or air/exhaust        valves), and may also contain special channels that could        deliver gaseous or liquid fuel and/or liquid water directly into        combustion chambers, when such a chamber is faced with the said        channels. The cavity within compressor body 130, which houses        compressor's piston 121, is defined by intersection of two arcs        with center at upper drive shaft 127, and lower drive shaft,        128. The radius of the arc equals large radius of the        compressor's piston 121, (see below) plus, optionally, very        small clearance. The arcs are filleted with a radius equal to        the small radius of the piston (see below) plus, optionally,        very small clearance. Compressor body 130, contains openings        that connect the cavity, which houses compressor's piston with        cylindrical holes, which house combustion chambers (133 and        134).    -   Expander body 170, which houses combustion chambers 133 and 134,        expander's piston 122, and drive shafts 127, and 128. It has,        optionally, exhausts ports 143 and 144 (or air/exhaust valves),        and may also contain special channels that could deliver gaseous        or liquid fuel and/or liquid water directly into combustion        chambers, when such a chamber is faced with the said channels.        The cavity within expander body 170, which houses expander's        piston 122, is defined by intersection of two arcs with center        at upper drive shaft 127, and lower drive shaft 128. The radius        of the arc equals the large radius of the expander's piston 122,        (see below) plus, optionally, very small clearance. The arcs are        filleted with a radius equal to the small radius of the piston        (see below) plus, optionally, very small clearance. Expander        body 170, contains openings that connect the cavity, which        houses expender's piston, with cylindrical holes, which house        combustion chambers (133 and 134).    -   Separator, 140. It should be noted that compressor body 130,        expander body 170, and separator 140, could be manufactured as        one single body.    -   Compressor cover 110, which may house all or part of PCM (not        shown);    -   Expander cover 180, which may house all or part of PCM (not        shown);    -   Two compression chambers 131 and 132, formed by space between        compressor body, 130, compressor's piston 121, separator 140,        and compressor cover 110;    -   Two expander chambers 171 and 172, formed by space between        expander body 170, expander's Piston 122, separator, 140, and        expander cover, 180;    -   A compressor piston 121—a solid body, or, optionally, a solid        body surrounded in a whole or in part by a liquid; the said        compressor piston 121, moves within compressor body 130, and        separates air cavity into compression chamber 131, and        compression chamber 132. The outer and preferably inner surfaces        of this piston are derived as follows: starting with an        equilateral triangle, draw three circles of same (relatively        small) diameter, where each circle is centered at each corner.        Draw three larger arcs centered at each corner so that the        larger arcs are tangential to any given pair of small circles.        The outside curves of the resulting shape consist of 6 arcs, and        are the shape of our piston. The resulting shape is similar to a        Reuleaux triangle, as is used in the Wankel engine, but with        rounded apexes. The piston constructed in this way has constant        width, defined as a chord drawn between opposing large and small        arcs and passing through the center of these arcs. The internal        curved surface of a piston may have three gear segments. They        are not connected with each other, and in the course of piston        rotation around the drive shafts, only one segment fully engages        with a gear of one of the drive shafts. Only at the end of        compressor's piston travel are both drive shafts partially        engaged with two gear segments. The motion of this piston within        the combustion chamber can be described as consecutive rotations        around two axis defined by the drive shafts. The alternative        ways (without gearing segments) may include grooves and cams or        be similar to the driving means of Wankel engine.    -   The expander piston 122 is constructed in a similar way as the        compressor piston described above, except that it is located        within the expansion body 170.    -   Upper and lower drive shafts 127 and 128, engage gear segments        of both compressor's piston 121 and expander's piston 122. In        simplest case, when both pistons move in phase, the pinion gears        of drive shafts are synchronous, with each other, i.e.        mechanically coupled. If pistons move out of phase, as will be        explained below, gears operating on compressor side of the        engine could be driven separately from gears operating on        expander side.    -   Air intake ports 141 are just windows within compressor body        130, and/or within compressor cover 110.    -   Exhaust ports 143 and 144, are just windows within expander body        170, and/or within expander cover 180. They could be,        optionally, connected with ERS.    -   Liquid (water) may partially or completely fill the inner space        of compressor's piston 121, and/or expander's piston 122.

Depending upon the position of the compression piston 121, the volume ofcompression chambers V₁₃₁ and V₁₃₂ varies from V_(Intake), duringinitial phase of intake stroke, to zero at the end of intake stroke. Thevolumes of compression chambers V₁₃₁ and V₁₃₂ are complementary, i.e.,V₁₃₁+V₁₃₂=V_(Intake).

Similarly, depending upon the position of the expansion piston 122, thevolume of expansion chambers V₁₇₁ and V₁₇₂ varies from V_(Exhaust),during initial phase of Exhaust stroke, to zero. The volumes ofexpansion chambers V₁₇₁ and V₁₇₂ are complementary, i.e.,V₁₇₁+V₁₇₂=V_(Exhaust).

It should be noted that, since piston does not have to be cylindrical,VExhaust to VIntake ratio, adjustable by size, shape and thickness ofthe compressor's piston 121, and expander's piston 122, could beselected in such a way that the pressure of expanded combustion productsat the end of the expansion stroke is close to atmospheric.

Operation

In spite of a different looking design, this engine operates in asimilar manner as the engines described previously. The details of theoperations follow.

We start the description of this engine's operation by looking into theexpander's side (FIG. 29b )) at the position where the expander's piston122, is moving clockwise. The expansion piston is driven by pressureexerted by combustion products. These products expand into expansionchamber 172 from the combustion chamber 134, through the channelconnecting the expansion chamber with combustion chambers.

At the same time, expander's piston 122, pushes the already expandedgasses out of chamber 171, through the exhaust port, 144.

In the simplest case, both pistons move in phase (their curved surfacesare concentric). Therefore the compressor's piston 121, (FIG. 29a )),moves in the same direction as the expander's piston (however, since weare looking now into a compressor side, the rotation of the piston iscounter-clockwise). In doing so, it is compressing the air located incompression chamber 131, and inducting air into compression chamber 132.

In more complex instances, pistons could move out of phase or even inopposite directions, if driven by four coupled shafts. This approachgives more flexibility in designing the shape of the combustion chamberas well as the timing of when compression occurs with respect to whenexpansion occurs. For instance, it is advantageous to start theexpansion closer to the end of compression stroke, when most of thetorque is required and is available. This will alleviate therequirements for the flywheel, or even eliminate it all together.

Coming back to the in-phase operation of pistons, the four chambers ofengine are undergoing four different strokes:

Compression chamber 131—compression stroke;

Compression chamber 132—intake stroke;

Expander chamber 171—exhaust stroke;

Expander chamber 172—expansion stroke.

These strokes will be completed when both pistons simultaneously reachtheir end points of the stroke. The degree of angular rotation of thepistons, in this case, is controlled by the drive shaft and gearsegments on the pistons instead of by the PCM, as in other designs. Inthis position both upper drive shaft, 127, and lower drive shaft, 128,should momentarily stop.

Unlike in our other designs, the combustion chambers, 133, and 134undergo continuous, preferably constant speed, rotation. At the end ofthe stroke, the combustion chamber in which air was compressing intoshould be rotated to the “closed” position, i.e. the combustion chambercavity is disconnected from compression space. In case of in-phasedesign it is preferable to have at least two cavities within eachcombustion chamber, so when cavity in which air is being compressed intois rotated into “closed” position, the second cavity is rotated into“open” position for expander's piston 122, exposing later to highpressure combustion products. In his scenario, the piston does not haveto be stationary for any length of time—they just have to swap the axisof rotation and keep rotating in the same directional sense.

Only one cavity will be needed if out of phase design is used, as thereis ample time for the cavity to reach expansion chamber, while theexpander's piston 122, gets into the end of the stroke position for thiscavity.

While combustion chambers, 133 and 134, rotate, they pass through thefuel cavity (not shown) within the compressor body, 130, which containsgaseous fuel under low pressure. Additional small channels on thecombustion chambers, 133 and 134, act as a gas conduit to fill in thefuel cavity. Combustion chamber body serves as a shut off valve for the“gas main”.

Hot, due to compression, air is mixed with the gaseous fuel and becauseits temperature is above the auto-ignition temperature of the fuel,spontaneous combustion occurs. Optionally, water could be inserted intothe combustion chamber (before during or after combustion) by filling inthe connecter channel space between the combustion chamber and expansionchamber with water (not shown) which would help to reduce momentarylosses related to initial small opening size between combustion chamberand expander body, 170. The losses—in a form of a heat—would beconverted into additional steam, and this energy will be recoveredduring the expansion cycle.

Rotation of combustion chambers, 133 and 134, takes sufficiently longfor complete combustion to occur. After the momentary pause, each pistoncontinues its rotation around corresponding drive shaft: i.e. if motionbefore the stop was around upper drive shaft, 127, it will be continued,but this time around lower drive shaft, 128. Note that combustion, andtherefore expansion, occurs on every “swing” of the pistons.

Implementations of HCCE described above results in the followingbenefits:

-   -   Compressing air, rather than air/fuel mixture, allows for a very        high compression ratio (15 to 30+). Fuel is introduced        separately into the combustion chamber.    -   Optionally injecting water into a compression chamber (131 or        132) during the compression stroke lowers the work required to        compress the air and brings the process closer to isothermal        compression.    -   A separate, constant volume combustion chamber allows for        isochoric combustion. If water is added to the combustion        chamber before combustion is complete, then, combustion will        occur under the condition of reduced volume (due to evaporating        water), which is even more efficient than isochoric combustion.        This water also lowers the temperature of gases in the        combustion chamber, which lowers the emission levels of NOx, and        allows for lower grade materials that could be used for        construction of the engine.    -   There is additional pressure during expansion, due to steam        formed during the combustion and expansion processes.    -   Exhaust pressure is low because the expansion volume is larger,        2 to 5 times than the intake volume, which is easily        accomplished because the expander is separate from the        compressor.    -   Energy Recovery System can be implemented as described above.

Modifications

In addition to trivial changes in forms or shape of various elements,there are other modifications that may have practical interest. Thereare numerous ways to drive pistons.

Also, of particular interest may be the design shown in FIG. 32. Herecompressor body, 130, may have protrusion(s), 111, into compressionchamber, shown in FIG. 32. Alternatively, this protrusion may be locatedon compressor cover, 110. This protrusion does not interfere withcompressor's piston 121, during its course of motion. It could be usedto house various additional element(s), such as, but not limited to:

-   -   Additional shaft(s) that may go through protrusion to provide        independent motion to compressor's piston 121, and expander's        piston 122;    -   Heat exchanger to remove the heat from the compressor. The water        that may be contained in the space between the compressor's        piston 121, and protrusion, 111, would flow through such a heat        exchanger driven by the motion of the piston;    -   Water pump—similarly to above, but without heat exchanger;    -   A Freon compressor, for air-conditioning system. Freon would        fill the space between the compressor's piston 121, and        protrusion, 111, and would be driven by the motion of the        piston. Protrusion may be made with fluidic valves that would        guarantee one way flow of Freon; and    -   An air compressor—similarly to Freon compressor above, but for        compression of air. It could be used as a stand-alone air        compressor or as a turbocharger for pre-compressing the air if        variable compression ratio is desired.

Similarly, expander body, 170, or expander cover, 180, may have aprotrusion for the same or different purposes as protrusion forcompressor body.

Another modification relates to a number of ways the drive mechanism(s)enable rotors/pistons to perpetrate the required motion. Non-circulargearing mechanisms or gear/cam combinations known in industry [3] may beemployed to slow down the rotor at the end of the stroke and toaccelerate it in the beginning of the next stroke.

A different embodiment, employing cams only is shown in a FIG. 33. Inthis design, the rotor has three cam followers, which ride on thesurface of a cam. It is possible to implement the positive drive (i.e.position of cam fully defines position of the rotor) with a single, dualor triple cams. For a single cam, the cam followers should be locatedwithin the equilateral triangle.

The rotor, as in previous design may run on a guide bearing or,alternatively, it may run without them, in which case the housing of theengine will serve as a guide. There may be many other configurations,which utilize cam and roller arrangements. For instance, the internalsurface of the rotor could be used as cam, while rollers are mounted onrotating plate or arm.

Constant Width Chamber Design

Another embodiment of HCCE, is shown in FIG. 36-40. This time, themodified Reuleaux triangle is used as engine's body configuration,compression side and expansion side. FIG. 38 demonstrates the geometryof the engine and the piston. The piston is of two-lobe design, were twoarcs equal to small arcs forming the modified Reuleaux triangle, whilelarge arcs are equal to large arcs forming the modified Reuleauxtriangle. The distance between small arc centers equal to the side ofequilateral triangle on which the modified Reuleaux triangle is build.The piston is driven by the rollers located on the crankshafts, 191.Both crankshafts that drive compressor's piston 121, and expander'spiston 122, could be mechanically coupled, so that pistons may keepconstant relationship to each other. The piston rotates consecutivelyaround three points forming the basis of modified Reuleaux triangle.

It should be noted that the expander's piston 122, may have a largersize (larger modified Reuleaux triangle) than the compressor's piston121. This means that if we locate the fixed combustion chamber withinthe corner of separator, 140, and equip it with one-way air valves, andif expander's piston 122, is 60 degrees out of phase, the saidexpander's piston would close the exit from the said combustion chamberand serve as the valve itself. If one then uses one-way air valves inthe compressor cover, 110, then only one valve for exhaust should bebuilt.

FIG. 39 shows a modification of this design, in which there are threeair/exhausts valve. Note that neither air intake or exhaust ports areshown on this Figure It should be also noted that because the intakevolume to total engine volume is the highest among the discussedconfigurations so far and because the engine in this configuration will“fire” three times per equivalent revolution of output shaft, the powerdensity is expected to be very high.

Finally, with respect to this modification, it should be stated thatmany different combinations of Constant Width Piston Configuration withConstant Width Chamber Configuration are possible and could yield usefulproperties.

Scissor Pistons Design

Finally, we describe and embodiment that enables HCCE to execute therequired cycle with configuration known in industry as “scissors” or“cat & mouse”.

The basic idea behind this approach is shown schematically in the FIG.41. In this configuration there are two pairs of pistons; each pairconsisting of one compressor piston and one expander piston, which aremechanically coupled so that pair rotates like one object. There is alsoa separating plate between compressor side and expander side; this platecontains Combustion Chamber cavity. Three independent drive mechanismsdrive two pistons pairs and separating plate (not shown for clarity).The housing contains fixed intake and exhaust ports and fuel port (noneof them are shown for clarity). The compressor compresses the air infront of the moving piston while simultaneously inducing the air throughintake port in the back of the piston. Air is compressed into acompression chamber, which is formed by the cavity of separating plateand one of the expander pistons and two compressor pistons. (See FIGS.42A and 42B, which describe the sequence of piston positions). The fuelis then injected or introduced into it and combustion begins andproceeds to completion. Meanwhile the separating plate shifts forwardand is now located between one compressor piston and two expanderspistons. When combustion is completed under constant volume, theexpansion cycle begins.

It is possible to construct the HCCE to execute the required cyclewithout the need for a standalone rotating combustion chamber with a“single-decker” design (not shown) in which a pair of piston moves in“scissor” configuration. The minimum separation between the pistons orcavity within one or both pistons forms constant volume combustionchamber. The expansion volume could be the same or, preferably largerthan intake volume, thus all elements of the cycle are implemented. Asskilled artisans would appreciate, the drive mechanism for both of thesevariations could be build using planetary non-circular gears orplanetary circular gears and cams known in the art.

Some other modifications applicable to many design configurations, orother applications of design geometries discussed above are:

-   -   The system could be built which stacks up several engines        together (“multi-cylinder” configuration) by adding additional        compressors/expanders with corresponding pistons. The        “cylinders” of such a system could be connected via        electromagnetic or mechanical clutch and could be turned on/off        if more/less power is required;    -   Compressors or pumps could be built on the basis of mechanisms        discussed above. They could be used in stand alone applications        or could be driven by the engine in question. One particularly        useful configuration of refrigerant compressor could be built        using the same approach as used in constant width piston design        utilizing both compressor and expander: compressor would        compress a gaseous refrigerant and after refrigerant is cooled        by external heat exchanger, it would be expanded and cooled in        the expander—returning significant portion of energy spent on        compressing back into the system. Such a system may be        particularly applicable for carbon dioxide as lot of energy can        be extracted during the expansion of this refrigerant.    -   The compressor body 130, and expander body 170, could be made        out of one solid piece, or alternatively out of, say, low        friction ceramic inserts, housed by aluminum frame. compressor's        and expander's pistons, theoretically, never even touch        compressor body 130, or expander body 170, so there is no        concerns for cracking the ceramics upon the impact.    -   The design of the engines described above (i.e.        compressor→combustion chamber→expander) may be suitable for        conventional rotary type engines, as it helps to solve the        problem with sealing of apex on a triangular piston employed in        such engines and may increase power density of such engines.    -   Other constant width or quasi constant width configurations        could be used for engine design, such as n-star piston with        (n+1)-star internal gears as the shape for compressor and        expander bodies (Gerotor).    -   Because compressor's piston 121, and expander's piston 122,        could run out of phase, it is possible to run compressor's        piston 121, at twice or triple the speed of expander's piston        122. If combustion chamber is equipped with one way air valves        135 and 136, and volume of combustion chamber space is        controllable, by adding more or less water into it or by some        other means, or if intermediate small air buffer is used, it is        effectively possible to control the power output (by giving up        some of the efficiency as condition #5, section “HCCE        Improvements”, will not be satisfied), by doubling or tripling        the intake volume.    -   The design can be reversed: Body becomes a modified Reuleaux        triangle (what we now call a piston) and piston becomes what we        now call a body. This is schematically shown on FIG. 34. It is        worthwhile to note that net effect of the movement of piston        around of stationary body is as if piston would roll around        three rollers (#1, #2, and #3). In this case Body executes three        consecutive rotations around three different center point,        located at the center of Reuleaux triangle, as indicated on FIG.        34b ).    -   When high temperature super-magnets, which are under development        in many companies, will become available, the body of piston(s)        could carry the imbedded super-magnets, see FIG. 40. These        super-magnets could be coupled directly to electrical generating        machine, which will need to have winding to correspond to        geometry of pistons and/or engine's body. If this is        implemented, there will be no need in PCM for applications that        generate electricity rather then mechanical motion. This could        prove to be especially useful for micro-engines, which could be        used as a power source for laptops, mobile phones, etc. This        magnetic coupling could be also applied to all modifications of        HCCE, described herein.    -   Briton cycle engines could use the geometry of either Constant        Width Piston Configuration or Constant Width Chamber        Configuration, or both. In this case the combustion chamber is        completely separate from compressor and expander and heat        exchanger that preheats compressed air before it enters into        combustion chamber, together with ERS could improve efficiency        even further.    -   Standard Wankel engines could use Constant Width Piston        Configuration to resolve sealing and efficiency problem due to        incomplete combustion.    -   Finally, modified Reuleaux triangle geometry may be used in        devices other than engines, pumps and compressors. For example,        a “triangular wheel” that rotates around two centers is shown in        FIG. 35. It is clear, that if vertical gears, attached to the        frame of the vehicle, are allowed to move with two different        speeds, the wheel will be moving on horizontal surface with        constant speed. The advantage of this wheel is that it is        equivalent in performance to wheel almost twice its size. At the        same time on uneven terrains such a wheel will have advanced        “all terrain” capabilities.

Additional Issues

In order to enable successful implementation of HCCE—it is useful toaddress a number of technical issues relating to combustion dynamics andsealing of the pistons and combustion chambers. These issues may ariseand be addressed for different embodiments of the engines discussedabove.

Combustion Dynamics

Fuel introduction, when hot compressed air “meets” stationary fuel canpresent a challenge from combustion dynamics standpoint: mixing of airand fuel, located in the wall of the housing could require additionaltime. Since combustion chamber may rotate at high speed at high loads,there might not be enough time for the air and fuel to mix properly.Similar problem may occur for fuel injection as well. To remedy thissituation it is possible to premix air and fuel before the compressionin the proportion, which will be below the lower limit of flammabilityof fuel in air. The flammability limits are different for differentfuels, but for Natural Gas (methane) the flammability limits in the airare typically 5-14% by volume. This means that we could pre-mix andcompress the air fuel mixture containing less than 5% (it is alsofunction of pressure) by volume without possibility for it toauto-ignite. Additional fuel, above the lower limit of flammability canbe injected or introduced via means described elsewhere in this patentapplication as well as international application publication number WO03/074840.

Pistons/Rotors Sealing—Fluidic Diode Seal (FDS)

Another issue that will need to be addressed is a sealing ofoscillating, rotating or recip-rotating parts, including the pistons andcombustion chambers. A ceramic type sealing used in Wankel engines couldpotentially be used for application in HCCE. In distinction with Wankel,due to geometry of HCCE engine, the seals do not necessarily have to belocated within the apexes of rotors, but could be located in stationaryposition near intake/exhaust ports.

In addition to this, since rotor of HCCE, based on modified Reuleauxgeometry, actually never has to touch the housing, a very small gap—onthe order of 0.001″—can be allowed between the rotor and housing. Theleakage associated with this gap will be small, especially at highengine RPM. In this approach we may not need a seal at all.

Finally, even this small leakage can be significantly reduced byapplying a fluidic diode concept for sealing purposes. Testa diode orany other suitable configuration fluidic diode can be used for thispurpose. Fluidic diodes as they are currently used in practice arestationary channels of special shape which create a significant pressuredrop for fluid flowing in one direction, while having very smallpressure drop when fluid is flowing in opposite direction. The ratio ofpressure drop when fluid flows in one direction to a pressure drop whenfluid flows in opposite direction, called fluidic diode's “diodicity”,can reach the level of 5 to 10.

As shown in FIGS. 43 a) and b), prior art fluidic diodes are formed bymaking a channel made of one smooth wall surface, while other wall has ashape or a feature that creates high pressure local area, but only whenfluid flows in one direction. FIG. 43a ) demonstrate conditions when theresistance to follow is minimal while in FIG. 43b ) the resistance islarge due to the local dynamics of the flow.

We will now apply the concept of fluidic diode to reduce the leakagebetween two bodies having a channel formed by the small gap betweenthem. If two bodies are in collinear motion with respect to each other,as shown in FIG. 43c-e ) and one or both of these bodies have featuresthat create locally high pressure for flow moving in one direction(leakage flow), such a feature would act as a dynamic seal withpotential to decrease the leakage 5 to 10 times.

Furthermore the Fluidic Diode Seal (FDS) concept can be improved evenfurther if channels of fluidic diodes are filled with liquid flowingthrough the fluidic diode in the direction approximately perpendicularto the relative motion of two bodies being sealed. Shown in FIG. 44 aretwo examples of fluidic diode seals, which could be, optionally, filledwith liquid. The choice of liquid should be dictated by the system inwhich seal being used. For example in engines described in thisapplication, the natural choice would be to use water as a sealingliquid. Another example would be to use refrigerant fluid in theapplication where Reuleaux triangle shaped piston is used as arefrigerant compressor; the FDS can be applied to both curved and flatsurfaces of such a rotor. Still another example would be to use engine'soil to implement a FDS as a replacement for ring seals currently used onall pistons in the ICE's—such a seal would not only function as a gasseal but also will lubricate cylinders, reducing the friction betweencylinder and piston, and enhance cooling of the piston and cylinder.

FIG. 45 demonstrates various examples of FDS that could be used to sealgases in the rotating combustion chamber for the engines described inthis application.

The invention may be embodied in other specific forms without departingfrom the spirit of essential characteristics thereof. The foregoingembodiments are therefore to be considered in all respects illustrativerather than limiting on the invention described herein. The scope of theinvention is thus indicated by the appended claims rather than by theforegoing description, and all changes that come within the meaning andrange of equivalency of the claims are intended to be embraced therein.

What is claimed is:
 1. A method of operating an internal combustionengine having a housing, a piston mounted in the housing for complexmotion about a plurality of axes and coupled to a shaft, and whereinoccur phases of compression, combustion, and expansion in the housing,and wherein, in the compression phase, air introduced through an intakeport into the housing is compressed by reducing volume of a compressionchamber in the housing from an initial volume to a second volume that isless than the initial volume, and wherein the housing includes anexhaust port through which are passed gases resulting from combustion offuel during the combustion phase, the method comprising: providing arecess in the housing and configuring the piston so that during thecomplex motion of the piston, the piston at least in part covers therecess during the combustion phase, at least a portion of the recessforming a constant volume combustion chamber; introducing the fuel intothe recess, the fuel mixing with compressed air to form a mixture ofcompressed air and fuel; igniting the mixture of compressed air and fuelin the combustion phase; and during the expansion phase, defining anexpansion chamber volume that undergoes expansion of gases fromcombustion while the expansion chamber volume increases to a thirdvolume that is larger than the initial volume; and wherein, over arotation of the shaft, the initial, second and third volumes are definedin differing amounts for the phases of compression, combustion andexpansion, in a manner that is smooth and continuous.
 2. A method ofoperating an internal combustion engine according to claim 1, whereinthe piston is a rotor.
 3. A method of operating an internal combustionengine according to claim 2, wherein the rotor has a plurality of lobes.4. A method of operating an internal combustion engine according toclaim 1, further comprising using an energy recovery system to increasetemperature of the fuel before it is introduced to the recess.
 5. Amethod of operating an internal combustion engine according to claim 4,further comprising using the energy recovery system to further reducetemperature of the gases from the combustion in the combustion phase. 6.A method of operating an internal combustion engine according to claim4, wherein using the energy recovery system further includes causingthermo-chemical decomposition of gaseous fuel.
 7. A method of operatingan internal combustion engine according to claim 4, wherein using theenergy recovery system further includes causing a catalyst-assistedreaction to occur at a temperature between about 450 degrees C. andabout 750 degrees C.